Off-brand eyepiences in Microstar IV (410)

[dtsh]

For starters, it's safe to presume I don't know much about this topic so take my observations for what they're worth.

I recently acquired a Microstar IV(410), this one badged as Leica. It came with a pair of Cat. 181 10x WF eyepieces which work great, but I would like a pair of 15x eyepieces. The "official" 15x eyepieces are Cat 182, but those seem to be difficult to locate.

While I am searching for a pair of 182 15x WF eyepieces, I decided to try out some of my other eyepieces to see how they performed, if at all.

To test, I have...
10x PL that came with an older microscope and the FOV is much narrower than 18mm, probably closer to 13 or 14. The eye relief on them is not good, but they provide a decent view and have a relatively sharp image at the edge.

WF10x-18mm generic eyepieces from...well I dont really remember where these came from. The image gets a little soft at the edge, but otherwise these compare quite well to the AO 181, though the FOV is a little narrower.

WF10X from my Olympus BHC. These show some softness in the image in the outer edges, the FOV is narrower (I believe 18mm), but aside from that they perform acceptably within the rest of the image.

AO Cat 146 10x, aside from some a very slightly smaller FOV and a bit of softness at the edge of the FOV, these seem little different from the 181's except that they appear to be ever so slightly wider in diameter and fit very snuggly in one tube and not at all in the other.

AO Cat 147 15x, unfortunately these would not fit in the tubes at all so I don't know how they would perform.

B&L 31-15-74 15xUWF, as with the AO 146, these fit very snug in one tube and not at all in the other. The view was pretty decent, a little softness at the edge of the FOV but otherwise seem to perform as expected.

So aside from the odd nature where some eyepieces just don't fit, it seems that I'm not as limited in options as I expected. I took a caliper and measured the Cat 181 eyepiece barrel diameter as 23.19mm and the Cat 147 (largest of them all) as 23.24mm, that's a closer tolerance than I would have expected. One could "fix" it if so inclined, but I am not currently so inclined.

The specs suggest that the 181 and 182 eyepieces are Huygens eyepieces, so it's not a big surprise that other eyepieces work tolerably.

Which brings me to my question, any 15x eyepieces you can recommend which are likely to perform well if I can't find the "right ones"?

[apochronaut]

The 181 and 182 eyepieces are not huygens. Huygens are two plano/convex lenses with the plano surface uppermost, separated by an air space with the focal plane between the two lenses. The only way you can have a W.F. huygens eyepiece is to increase the diameter of the eyepiece. Some of the low to mid-grade Chinese microscopes offer " w.f. " high magnification eyepieces, such as 20X in packages. These are often just huygens with a 30mm bore. Some stereo microscopes exploit that possibility in offering 5 or 6X eyepieces that do have a reasonable field of view, able to image slightly over a 30mm field with a 6X. Using a 23.2mm 5X eyepiece is like looking down a tube. At 10X , a really good 23.2mm huygens reveals usually around 14mm.

Most W.F. eyepieces are proprietary designs incorporating a wide field with adequate corrections for planarity. It isn't by accident that AO made an array of w.f. 10X eyepieces with different catalogue numbers. It is because the optical system that they are designed to complement requires certain positive or negative corrections, all the while maintaining a flat field. Sometimes, another eyepiece does in fact provide a similar correction to a native eyepiece but all too often, it is accompanied by curvature of field and sometimes even lateral ca. A case in point is the Bausch & Lomb 31-15-61 10X W.F. made to complement the Balplan Planachromat objectives. They seem very similar to the AO 180 or 181. In fact, the lens curvatures and or glass formulations are very different. The 31-15-61 correct well enough to the periphery when used in a Microstar/Diastar but provide a nice degree of pincushion distortion as a bonus.
The 181 has a plano/convex doublet eyelens and an assymetrical double convex singlet field lens. The B & L 31-15-61 has a plano/convex singlet eyelens with a very assymetrical double convex doublet field lens. Although the two designs achieve almost identical results when used to magnify the convergent rays in their designed system, , their formulas are very different and they do not do well in each other's systems.
The slightly narrow optical tubes on the Microstar head are not by accident. The intention was for users to retain the proper eyepieces that perform the best with the objective selection available for that microscope. There were 6 or seven other 10X W.F. choices and at least 3 other 15X W.F. choices in the AO stable, each designed to optimize a specific optical system. In their flagship diascopic microscope, they didn't want the " these will do" mentality taking hold. Cat. # 180 or 176 or 146 don't really work. Sometimes the error is subtle but it is still there, and when a customer was paying a couple or more thousand for an iris equipped planfluor 100X 1.30 oil immersion objective, AO wanted it to work it's best.
You are correct for instance that the old series 4 eyepieces , #146 work passibly good in a series 400 and they will just barely fit. However, the field is only 19mm which is tolerable but there is a small amount of ca at the periphery. Tiny, yes but still there. It's compatriot, the cat.# 147 W.F. 15X yields about the same amount of ca at the periphery but planarity falls off outside the central 50% of the field. Details at the periphery are outright blurry.
Moving closer in time with the cat.# 184, which was the W.F. eyepiece used in the 34mm parfocal system. That might be your best bet as an alternative. They look almost identical to the 182, even down to the slightly convex eyelens and do not deliver much in the way of lateral ca : almost imperceptible but they perform in other ways, much like the Bausch & Lomb 10X profiled above perform. They are not fully plan. They are, to about 18mm, then backwards curvature progresses rapidly to the point that details are blurred a bit at the edge, so there is some pincushion effect. The 182, is not also fully plan with certain objectives. Particularly the 10X planachro. It too has a slight backwards curvature of field, just at the edge. Pairing a 182 and 184 in a series 400 produces a hybrid effect and it is in fact not noticeable that there are two different eyepieces in, so they are pretty close. Oh yes, there is one other difference. The 182 are slightly brighter eyepieces. Another option is the B & L 31-15-62 15X W.F. They may even be closer to the 182, than the 184 and they improve the peripheral ca performance of the Reichert Austria objectives, something worth thinking about if a planapo or two ever come your way, or even some Austrian phase objectives.
There are Chinese knockoff objectives, usually sold for B & L but sometimes for both B & L and AO. Mostly these are 10X but I have seen 15X. My guess would be that they are for stereo microscopes, which are completely different eyepieces. Unless you had the opportunity to test them or knew a reliable source that tested them, I would shy away. B & L stereo mic. eyepieces generally perform poorly in their compound microscopes, so likely would too in a series 400, based on the performance of the Baplan eyepieces in one. Lateral ca would be the issue.

[geo_man]

Thanks apochronaut; i'm also interested in using 15x eyepieces in my microstar 410. Can you confirm that the CAT 184's will fit in both the narrow eyepiece tubes? Thank you!

[Plasmid]

A couple of months ago, I found myself in the same dilemma as you, wanting also to up the magnification my options were a 50X objective or a pair of Cat 182. I decided to pull the trigger on a pair of 15X eyepieces from AliExpress,paid $30 altogether and Im happy to report than aside from the smaller FOV the image is quite decent. As a matter of fact the videos that I normally upload are all shot using those 15X Eyepieces ona phone mount. I cant speak for how much lateral CA or distortion you will get with them and frankly most eyes wont be able to pick up on that unless you know what to look for., but for regular viewing you can't go wrong. If you are looking for a clearer image and dont care for the extra magnification there is a 10x23mm Super wide field eyepices that some members have ordered from China, not sure how they perform on a Microstar but worth looking at.
https://www.ebay.com/itm/273482756677
https://www.aliexpress.com/item/32482699713.html

[apochronaut]

The 184 eyepieces i have, are tighter than the 182s but they will fit. Ditto for the B & L , 31-15 - 62.

[dtsh]

Thanks for the info and good to know the eyepieces *aren't* Huygenian.

[apochronaut]

I just thought I would add a caution. I know there are more than a few people out there looking for 15X eyepieces for any one of the AO infinity microscopes. They are getting hard to find. I wince at the thought that quite a few systems with both 10 and 15X eyepiece sets went out to labs and the 15's sat in a drawer because they were never used. Eventually, the microscope was replaced, the old one went to surplus and later , "oh, what are these" "uh, they belonged to that old microscope.... just chuck 'em "
Patience is important. Beware of the many B & L 15X out there. You are going to see a lot of them because of the popularity of the steteozooms. The only one that works is the 31-15-62. It has the # stamped into the upper part of the housing and is almost impossible to read because it is black anodized after stamping. They have a much smaller eyelens than the AO 182 or 184. It is only 14mm across and slightly concave. The AO eyelens' are 20mm across and slightly convex. The B & L gives the same extra wide apparent field with just a slight bit less eye relief.
There are Leica eyepieces out there for stereozooms. They look very similar to the 31-15-62. They have a smallish concave eyelens( in fact 16mm diameter). They are marked in white 310564. Used to be 31-05-64 because it's a B & L eyepiece. Don't be tempted. They don't work. It is a correcting eyepiece and overcorrects when used in the series 400 optical system giving pronounced lateral ca. The 31-05-64 is almost neutral, maybe very slightly compensating with a small curvature inversion. The 184, very slightly compensating with slightly more curvature inversion. The 182, very slightly compensating with very low curvature inversion.

[Stomias]

A couple of weeks ago I bought a pair of B&L 15X W.F eyepieces for my Microstar. They perform great. They fit very tight in both the Microstar and my AO Spencer 26 stereoscope. Dangerously tight! Yesterday I took a bit off of the barrels (light sanding), polished and lightly lubricated (Facial oil from the side of my nose ) Before commenting on the "nose oil" I'll share this. I am a fly fisherman and sax player. Many, many years ago after occasionally having extreme trouble breaking down a rod (stuck ferrules) I read about rubbing male ferrule along the side or your nose. For 30 years after starting to do this as a precaution against stuck ferrules I've NEVER had that problem again. This on metal, graphite and fiberglass ferrules. The metal ferrules on some REALLY collectible (read expensive) cane flyrods were my main concern. Fast forward 30 years. Having the same problem with saxophone neck tenons (sticky, hard to remove, hard to turn) and trying all sorts of things suggested to avoid this problem, Someone suggested.......you know.....lubricating the tenon with a bit of facial oil. Again, problem solved forever. Now, with the eyepieces, I thought............................................................................................. Sorry for the long winded "lubrication" side track. Just thought it interesting.

[dtsh]

I tried a pair of B&L 15x WF and they do seem to perform pretty well, unfortunately these wont cut it for me as I am very sensitive to eye relief. The eye relief seems a few mm shorter than the 181's, but it's too short for me. If one of you is interested in a nice pair of B&L 15x WF eyepieces, send me a PM. They'll go up on eBay in a few weeks (assuming they don't end up in a drawer for a few years)

BL_15x_1.jpg (87.89 KiB) Viewed 4595 times

The hunt continues...

[apochronaut]

Those are stereozoom eyepieces. The very ones I warned people NOT to buy. The only ones that acceptably correct in the Microstar iV system are the ones marked 31-15-62.

[Stomias]

I now have 2 sets of the B&L silver eyepieces 15x and 20x. Not sure of the vintage or design. They work well in my Microstar IV.

https://photos.app.goo.gl/n9ZoLvntzVqjAGuj6

https://photos.app.goo.gl/FY3ETSUxXej68qWq7

[apochronaut]

I would have to see the eyepieces you have in order to determine what you have. If they are marked 23mm or 22mm, then they are older eyepieces designed for the latter 160mm system and early flat field system. Unmarked with only the magnification and field design, they could be a couple of others. Stereo eyepieces are sometimes marked as such and sometimes not. Those with slots in the eyepiece bezel are stereo eyepieces. The ideal with microscope eyepieces as opposed to telescope eyepieces is that the field should be completely flat and ca and distortion free. The only B & L eyepiece that approaches that ideal with Microstar IV optics is the 31-15-62 15X W.F. Most others over correct giving undesirable lateral ca or pincushioning or keystoneing, even coma and field curvature.
It all depends what your expectations of how a microscope optical system that is supposed to be plan are. Mine are that it is supposed to work as engineered.

[dtsh]

Thanks for the updated info, I'll see if I can acquire the correct ones and see if they work for me. Is the first of Stomias' images the correct one? I hate it when manufacturers don't label their stuff or, as in the case of many Microstar IV's label them in such a way that it will come off easily.

Without any model info, I was relying on guesswork. They seem to work reasonably well in the Cycloptic at least, but they will probably end up on eBay.

[apochronaut]

Microscope eyepieces mfg. after the era when Kellners were used as a W.F. option by a few companies, are by and large proprietary designs, highly tuned to the optical system that preceeds it. Even if an eyepiece is required to be neutral in terms of it's corrections for lateral ca, it more than likely won't be the same as another neutral eyepiece due to considerations involving field flatness, or front focal length to name a couple of the conditions.
Both B & L and AO used both corrective and compensating eyepieces with their zoom stereo systems. Corrective with the lower priced units such as stereozoom 3 and AO 569, compensating with strereozoom 7 and AO 580. However, that's a kind of black & white picture because the degree of corrections or compensation is more or less, depending on the objective design. You can't easily swap the eyepieces around and get accurate performance.

Are your eyepieces not marked dtsh? If the eyelens is 17mm across they are likely 31-05-62, which are correcting. They might be 31-05-68 which has a smaller eyelens than the former but might work better on a Microstar although there would be ca and probably pincushion. The eye relief is a bit tight with the 62 but not too bad with the 68, although the AO 182 is better than either.
The two eyepieces that Stomias has are stereo eyepieces. The 20X is a 31-05-63 which is compensating, meaning that they work passably on a Microstar IV. The design was used with the stereozoom 3,4,5 and 7. On a Microstar it starts to exhibit lateral ca and lack of planarity visually less than 1/2 way to the peiiphery. At about 90% the image is very blurry and kind of rolls backwards displaying more of a pillow cushion effect than a pincushion effect. If you didn''t have a 20X, they could do in a pinch but the f.o.v. would be restricted.
The older 15X one with the pin wrench bezel is likely an older version of the 31-05-62. They changed from the pin wrench bezel to the slot version in the 80'S some time.

[dtsh]

Microscope eyepieces mfg. after the era when Kellners were used as a W.F. option by a few companies, are by and large proprietary designs, highly tuned to the optical system that preceeds it. Even if an eyepiece is required to be neutral in terms of it's corrections for lateral ca, it more than likely won't be the same as another neutral eyepiece due to considerations involving field flatness, or front focal length to name a couple of the conditions.
Both B & L and AO used both corrective and compensating eyepieces with their zoom stereo systems. Corrective with the lower priced units such as stereozoom 3 and AO 569, compensating with strereozoom 7 and AO 580. However, that's a kind of black & white picture because the degree of corrections or compensation is more or less, depending on the objective design. You can't easily swap the eyepieces around and get accurate performance.

Are your eyepieces not marked dtsh? If the eyelens is 17mm across they are likely 31-05-62, which are correcting. They might be 31-05-68 which has a smaller eyelens than the former but might work better on a Microstar although there would be ca and probably pincushion. The eye relief is a bit tight with the 62 but not too bad with the 68, although the AO 182 is better than either.
The two eyepieces that Stomias has are stereo eyepieces. The 20X is a 31-05-63 which is compensating, meaning that they work passably on a Microstar IV. The design was used with the stereozoom 3,4,5 and 7. On a Microstar it starts to exhibit lateral ca and lack of planarity visually less than 1/2 way to the peiiphery. At about 90% the image is very blurry and kind of rolls backwards displaying more of a pillow cushion effect than a pincushion effect. If you didn''t have a 20X, they could do in a pinch but the f.o.v. would be restricted.
The older 15X one with the pin wrench bezel is likely an older version of the 31-05-62. They changed from the pin wrench bezel to the slot version in the 80'S some time.

Unfortunately they are not labeled. Both are identical, so I showed both sides in the image above.
My calipers read 0.659" (16.74mm) across the inside of the retaining ring, so I am guesing they are probably the 31-05-62.

I suppose at some point I should just start imaging through them to get something a bit more useful.